Table 5.

Main results of systematic reviews focused on the link between shift work and smoking habits.

References, Country	Type - Shift work (n)	Assessment of outcomes (n)	Confounding factors (n)	Main results shift work vs. day work (n)
Boggild and Knutsson (21), Nordic countries	Unspecified (16)	Smokers, % (14) Cigarettes/day (2)	NA	Tobacco consumption: - Cross sectional studies: Significantly higher (6), lower (1), no difference (5) - Prospective studies: at baseline of studies: higher (2); After 6-months follow-up, no difference of number of new smokers and no change habits (1)
Zhao and Turner (32), Australia	Permanent night (2) Rotating (2) Evening (1) Unspecified (3)	Smokers, % (5) Cigarettes/day (2)	Adjustments (1) MD (6)	- Shift work: current smokers OR = 1.3 (1.1–1.6) (1) - Rotating shift: current smokers: 40 vs. 34.3%, p = 0.058 (1); % of every day smokers: NS (1) - Permanent night: more likely to smoke and smoked significantly (p < 0.01) more cigarettes/day (1) - Shift work: significantly higher tobacco consumption, p = 0.027 (1) - Shift work: after 1-year follow-up, significantly higher number of cigarettes/day (1)

(n), Number of studies concerned; MD, Missing Data; NA, Non Adjusted; NS, Non Significant.